This change amends it so we use a static service to keep track of
the typing presence.
It correct various edge cases the initial implementation had
- Faster close messages
- When composing on topic 1 and viewing topic 2 we had incorrect
presence
- Changing a running composer to reply as new topic or reply to a
differet topic would not correctly shift presence
Authored by tgxworld, with contributions by sam
Guo Xiang Tan
9e827eb420